Production Unit Development Overview
===

###### 2019-11-01

This is a document recording notes for the path to creating a working production unit.

Hardware
---

* Get SIM5320A GPRS/GPS working
  - Need to automatically start and connect on boot
  - Need to confirm GPRS antennae and GPS antennae work inside or at other positions
    in housing
  - GPRS needs to have some pin tied for automatic power on (potentially rpi controlled)
* Connect/stack SIM5320A in line with screen
  - make sure screen and serial have no physical pin conflicts
* Make breakout board for power connector
* Find solution for speaker amplifier
* Need to figure out case. Stop-gap of retrofitting to current case
  - New case need only to attach to the four screw configuration already in place for
    DIU bottom plate
* Look into brighter screen

Software
---

* Add 'quick dim' feature to screen
  - Screensaver will light back up on press
* Better screen diagnostics
* Debug/testing of driver interface

Progression
---

Instead of replacing the whole system in one iteration, I think
it's better to replace certain components individually over time.

The rough outline is as follows:

* Replace the DIU with an updated piece of hardware
  - If possible, a new case should be used but the old
    case can be re-used if the need for replacement DIUs
    is pressing
  - There should be an old style connector for backwards
    compatibility
  - There should be a new style PIU and power connector.
  - There should be either an adapter to connect to the old
    style connector or have all connectors available

